An Asymmetric Synthesis of the Ant Venom Alkaloid(3S,5S,8aR)-3-Butyl-5-(4-pentenyl)indolizidine via the Sharpless Asymmetric Dihydroxylation
摘要:
The first asymmetric synthesis of the ant venom alkaloid (3S,5S,8aR)-3-butyl-5-(4-pentenyl)indolizidine (1) has been performed by starting with the Sharpless asymmetric dihydroxylation of N-alkenylcarbamate (3) followed by reductive annulation (5-exo-tetrahedral).
(-)-Monomorine I has been synthesized using a stereoselective intramolecular 1,6-conjugate addition of a hydroxylamine to a dienyl ester, followed by a tandem hydrogenation-lactamization reaction. Michael addition - tandem reaction - alkaloid - lactam - heterocycle
Synthesis of alkylated indolizidine alkaloids via Pummerer mediated cyclization: synthesis of (±)-indolizidine 167B, (±)-5-butylindolizidine and (±)-monomorine I
The syntheses of indolizidine alkaloids, i.e., (+/-)-coniceine, (+/-)-indolizidine 167B, (+/-)-5-butylindolizidine and (+/-)-monomorine I via Pummerer cyclization are described. The key step is the transformation of lactam sulfoxide to bicyclic lactam via the Pummerer cyclization. (C) 2007 Elsevier Ltd. All rights reserved.